Seedlings of M. quinquenervia were obtained by germinating seeds collected from trees in south Florida. Plants from each chemotype were obtained from vegetative cuttings from trees whose chemotype had previously been determined by gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS). All plants were transplanted into larger pots (11.4 L) when about 25 cm tall. These plants were fertilized with 90 g/pot Osmocote Plus 15-9-12, N-P-K (Scotts-Sierra Horticultural Products, Marysville, OH) in a slow-release 'southern' formulation . Plants were grown in a screenhouse that received rainwater and daily irrigation from overhead sprinklers for approximately 6 months at which time the plants were about 1 m tall. Three times weekly, leaves were clipped from trees and brought back to the laboratory. As O. vitiosa is a known Xush-feeder, only the silky terminal 15 cm tip leaves of each tree were collected and either used for plant quality analysis or fed to larvae.

M. quinquenervia chemotypes were distinguished by the principal terpenoids E-nerolidol and viridiflorol using gas chromatography and mass spectroscopy. Not only were the terpenoid profiles of the two chemotypes different but the viridiflorol leaves had greater toughness (1.2-fold) and reduced nitrogen (0.7-fold). When the larvae and adults were fed leaves of the E-nerolidol chemotype increased adult biomass (1.1-fold) and fecundity were found (2.6- to 4.5-fold) compared with those fed leaves of the viridiflorol chemotype. Regardless of the larval diet, when adults were fed the E-nerolidol chemotype leaves they had greater egg production compared with those adults fed the viridiflorol leaves. Moreover, adult pre-oviposition period was extended (1.5-fold) when individuals were fed the viridiflorol leaves compared with those fed the E-nerolidol leaves. By rearing the O. vitiosa weevil on the more nutritious chemotype plants these results assisted in the mass production and establishment of the M. quinquenervia biological control agent.

Plant material: Leaves of M. quinquenervia were collected from January to October during the ten year period (1992-2001) on mainly East part of Madagascar island and in particular on Toamasina, Mananjary, Manakara, Farafangana, Vangaindrano, Moramanga, and Ambatondrazaka locations. Olfactory chemotype selection: During the years 1992-1995, since the price for (E)-nerolidol and viridiflorol chemotypes was very strong, leaf collection was done on trees chosen after olfactory selection by a chief harvester who compared the olfactory threshold of crumple leaves with our clearly identified oil samples. After 1996, collection was done at random and no particular attention in leaf harvesting was taken.

Niaouli essential oils from Madagascar were classified into three chemotypes using Principal Component Analysis (PCA): a cineole chemotype (49-62%), a viridiflorol chemotype (21-36%) and an (E)-nerolidol chemotype (56-95%). The 1,8-cineole chemotype is widespread, representing 92% of the samples investigated if the leaf collection is done at random.